An electric vehicle includes an electric motor for driving the rotation of a wheel of the electric vehicle, and it is necessary that a battery serving as a power supply for the electric motor be mounted in the electric vehicle. Patent Literature 1 discloses a charging technique, in which a battery charger is always connected to the battery while the vehicle is in storage since the state of charge of the battery decreases due to self-discharge even though the battery is simply left unused. In the charging technique of Patent Literature 1, the battery charger is connected to the battery in a state where the battery is mounted to the vehicle body.